Alkyl dibenzothiophene sulfonic acid



Patented Oct. 24, 1950 2,527,335

Frederick P. Richter and Everett W. Full'cr, Woodbury, N. J., assignorsto Socony-Vacuum Oil Company, Incorporated, a corporation'of New York INo Drawing. Original application June 24, 1947," Serial No. 756,812.Divided and this application August 20, 1948, Serial No. 45,426

. V l I This invention relates to alkylated dibenzothiophene sulfonicacids, to metal salts thereof, and to a method for preparing the same.More particularly, the present invention is concerned with lubricatingoil compositions improved by incorporating therein a small proportionsufficient to improve the properties thereof of one or more of theaforesaid compounds.

In accordance with the present invention, it has been discovered thatdibenzothiophene can be alkylated under certain conditions by contactingthe same with an alkyl halide in the presence of a Friedel-Crafts typecatalyst to produce alkylated dibenzothiophenes.

'It has further been discovered that the alkyl dibenzothiophene producedas described above can be sulfonated by contact with a suitablesulfonating agent, such as chlorosulfonic acid, concentrated sulfuricacid, oleumfand the-like.

Still further, ithas been discovered that metal salts of the alkylateddibenzothiophene sulfonic acid, produced as a'result of the aforesaidreaction, can be prepared upon contacting said acid with aninorganic'salt or hydroxide of the desired metal. It'has been furtherfound that certain of said metal salts, notably those of the alkali andthe alkaline earth metals, are useful as mineral oil additives and,moreparticularly, are effective as detergents in motor lubricating oils.j

The compositions'ocf this invention are pre pared by using as a startingmaterial substan tially pure dibenzothiophene or a crude product whichcontains a major proportion of dibenzo thiophene. This starting materialis alkylated in accordance with the present invention by bringing thesame into contact'with an alkyl halide and a Friedel-C-rafts catalyst,preferably in'the presence of an inert organic solvent such as Stoddardssolvent.

The orientation of the alkyl group in dibenzothiophene has not beenestablished with certainty. Indications are, however, that when only onehydrogen in each molecule of dibenzo thiophene is replaced by an alkylradical, the entering alkyl group occupies. the 2- or33-position andthat when two hydrogens are replaced with alkyl groups, the enteringradicals occupy the 2- and 8 -positionsor the 3-. and '7-positions.

The orientation, however, does not appear to be of too greatsignificance in'the practical syn-- thesis of oil additive compositionsprepared from the dibenzothiophenes so alkylated.

.The initial ratio of alkyl halide to diben zothiophene can 'be variedover widelirnits and.

'7 Claims. 7 (01. 260329) the degree of alkylation thus controlled toyield m ono-, di, and polyalkylated dibenzothiophenes. Generally,however, a ratio of'l to 3 gram atoms of halogen, as combined in thealkyl halide, per mole of dibenzothiophene has been found to bepreferable. Alkylating agents of lower halogen content tend to result ina reduced yield of the desired alkyldibenzothiophene, while product ispractically nil; while at temperatures above about 85 0., a tarformation becomes predominant; causing a substantial decrease intheyield of desired product. Accordingly, the temperature range of fromabout 20 C. to about 85 0. appears to be a critical factor in thesuccessfulalkylation of dibenzothiophene. Particular preference isaccorded to temperatures in the range of from about C. to about 0.,since under these conditions the reaction was found to proceed at afaster rate, and consequently as apractical matter, to yield a greateramount of alkylated dibenzothiophene per unit time as compared withlower temperatures in the operable range. a

The use of an inert organic solvent, while not absolutely necessary, hasbeen found to be highly desirable in modifying the alkylation ofdibenzothiophene, causing,a substantial decrease in the. formation ofundesirable tar as the c0ndensa-.,

as-well as economical reasons, the use of alkyl' halides of hydrocarbonsin the paraffin wax range having from about 20 to about 30 carbon atomsrepresents a preferred embodiment of this invention. Such alkyl halideshaving molecular weights in' excess of about 250 and having more thanabout 20 carbon atoms in their molecules are well known. Chlorinated waxmay be considered as a preferred example of such compounds and, inparticular, those waxes in which the degree of chlorination has been soregulated that the final chlorinated wax generally contains betweenabout 5 and about15 per cent chlorine.

The alkylated dibenzothiophenes described R will represent an alkylradical in the paraflin wax range having a chain of 20 to 30 carbonatoms, and R, will likewise represent a hydrogen atom or an alkylradical in the paraffin wax having'a chain of 20 to 30 carbon atoms.

The metal alkyldibenzothiophene sulfonates described above have beenfound to be particularly useful in lubricating compositions where abovemay, in accordance with this invention, be

sulfonated by dissolving in a suitable solvent and adding thereto asulfonating agent such as chlorosulfonic acid. Concentrated sulfuricacid, oleum, or the like may also be used for sulfonating and may beemployed directly. The ratio of sulfonating agent toalkyldibenzothiophene may be varied over a wide range to yield productsof various degrees of sulfonation. In general, however, a ratio of 1 to2 moles of sulfonating agent per mole of alkyldibenzothiophene ispreferred. The addition of sulfonating agent to the solution ofalkyldibenzothiophene usually is conducted at ordinary roomtemperatures, that is, between about C. and about 30 C. Upon finaladdition of the sulfonating agent, the mixture is suit ably heated underreflux for a period to insure complete reaction. The solvent employedmay then be recovered by distillation. The residue obtained from saiddistillation is an alkyldibenzothiophene sulfonic acid. I

In order to prepare metallic salts thereof, the alkyldibenzothiophenesulfonic acid as prepared above is dissolved in a suitable solvent, suchas a refined petroleum oil, and the solution of sulfonic acid isconverted to the desired metal salt by simple neutralization thereofwith a metal hydroxide, carbonate or other alkaline inorganic salt ofthe metal. Alternatively, synthesis of the desired metal salt may beaccomplished by metathesis of an alkali metal sulfonate prepared by oneof the above mentioned methods with an inorganic halide of the desiredmetal.

The temperature at which the metal salt of alkyldibenzothiophenesulfonic acid is prepared will generally be in the range of from about50 C. to about 200 C. and preferably between about 85 C. and about 150C. The reaction mixture is maintained at an elevated temperature in theabove range until all of the water of reaction is removed. During thisoperation, it is desirable but not necessary to bubble an inert dry gassuch as nitrogen through the mixture in order to where R is an alkylradical, R is selected from the group consisting of hydrogen and analkyl radical and M is one equivalent of a metal. More specifically,where the metal salts are intended for use as additives in petroleumoils, M will represent an alkali or an alkaline-earth metal and theybehave as detergents in maintaining the cleanliness of an engine.

These materials may be incorporated in any lubricating compositionranging from gasoline and kerosene to heavy gear oil, petroleum wax, andpetrolatum. They may also be used with similar lubricating compositionsderived from other animal, mineral, or vegetable sources, or preparedsynthetically. Such lubricating compositions may contain any otherdesired addition agent or combination of addition agents which may beadded for the purpose of effecting the same improvement or otherimprovements in that composition. Ordinarily, the new compositionsdescribed above will be added to mineral oil fractions in amountsranging from about 0.1 to about 5 per cent but may be added in amountsup to 10 per cent in some instances. Those of the new productswhich aresufliciently soluble in oil may be marketed in the form of oil concentrates, in which the percentage of the new products is greatly inexcess of that which is desired in the final lubricating composition,for example, quantities up to about per cent'by weight.

Further details and advantages of this invention will be apparent fromthe following illustrative examples: 7

Example 1 Petroleum wax of A. S. T. M. melting point of 125 F. waschlorinated by introducing chlorine gas at about 100 F. until 12 percent by weight of chlorine was adsorbed therein. 596.6 parts by weightof the chlorowax so obtained were slowly added to a mixture'of 184 partsby weight of dibenzothiophene, 596.6 parts by weight of Stoddardsolvent, and 30 parts by weight of anhydrous aluminum chloridemaintained at a temperature of C. The temperature was allowed togradually rise during the addition of the chlorowax to -85 C., in whichrange it was held during the alkylation. The mixtur was agitated for aperiod of 4 /2 hours in this temperature range, after which time theactive evolution of hydrogen chloride had practically ceased. To thecooled alkylation mixture, 500 volumes of 20 per cent aqueoushydrochloric acid were slowly added and the resulting mixture was heatedto a temperature of C. to hasten the separation of the mixture intoorganic and aqueous layers. After said separation was -effected,'themixture was cooled and the aqueous layer was drawn off anddiscarded. Theremaining organic layer'was washed with water, filtered, and the solventdistilled off under vacuum. The dark green residue consisted of 706parts by weight of a diwaxdibenzothiophene having a, sulfur content of4.1 per cent, the calculated sulfur content being 4.0 per cent.

Two hundred parts by weight of the diwaxdibenzothiophene as preparedabove were dissolved nating'agent was complete, the mixture was amazesheated under reflux for a period 012% hours to complete the reaction.The chloroform was then recovered by distillation and the residue wasidentified as a diwaxdibenzothiophene'sulfonic acid having aneutralization number of 81, the theoretical neutralization number being82.

Example 2 The diwaxdibenzothiophene sulfonic acid as prepared in Example1 was diluted with 400parts by weight of an SAE 30 grade solvent-refinedjpe troleum oil and 9''! parts by weight of barium hydroxide octahydratewere added. The resulting mixture was held vat-a temperature of 85 C.for a period of 1 hour, raised gradually to 100 C. for 1 hour andfinally increased to 150 0., where it was held until all of the waterinthe reaction mixture had been removed. This required maintaining thereaction mixture at the temperature of 150 C. for an additional hour.During this operation a steady stream of dry nitrogen gas was passedthrough the mixturein order to facilitate the removal of the water. Theresulting hot oil solution was then filtered through Hi-Flo (a clay ofthe activated montmorillonite type represented by the ideal formula:

wherein n is an integer). The filtrate obtained from said filtrationconsisted of a petroleum oil solution of barium diwaxdibenzothiophenesulfonate having a barium content of 4.1 per cent and a sulfur contentof 2.6 per cent.

Example 3 The diwaxdibenzothiophene sulfonic acid prepared as in Examplel was reacted with magnesium hydroxide, in the same manner as describedunder Example 2, for the preparation of the barium salt. The resultingproduct was an oil solution of the magnesium salt ofdiwaxdibenzothiophene sulfonic acid. It analyzed to give 1.1 per centmagnesium, the calculated magnesium content being 1.0 per cent.

Example 4 A mixture consisting of 230 grams of a diwaxdibenzothiophenesulfonic acid, 23 grams of sodium hydroxide dissolved in 200 c. c. ofmethanol and 400 grams of a solvent-refined SAE 30 grade motor oil washeated under reflux with eflicient stirring for 2 hours. The methanoland water of reaction were then removed by distillation with a steadystream of dry nitrogen gas passing through the mixture until thetemperature reached 150 C. Final traces of methanol and water wereremoved by maintaining the temperature of the mixture at 150 C. with acurrent of dry nitrogen gas passing therethrough. The resulting hot oilsolution was passed through a filtering clay at a temperature of about95-100 C. in order to remove unreacted sodium hydroxide and otherinsoluble impurities. The product so obtained consisted of 520 grams ofa clear oil solution of sodium diwaxdibenzothiophene sulfonatecontaining 1.4 per cent sodium and 3.2 per cent sulfur.

The above described metallic salts are effective as detergents in motorlubricating oils, as is demonstrated by the following test: Blends weremade in a SAE 30 grade solvent-refined motor oil containing 0.75 percent by weight of an antioxidant additive, consisting of the reactionproduct of pinene and phosphorus pentasulfide similar to that describedin Example 3 of U. S. Patent 2,381,377. *The following blends wereprepared:

A. Oil plus 0.75 per cent antoxidant.

B. Oil plus 0.75 per cent antioxidant plus 5 per cent of the abovedescribed barium diwaxdibenzothiophene sulfonate.

C. Oil plus 0.75 per cent antioxidant plus 2 per cent of the abovedescribed magnesium "diwax- (libenzo'thi'ophene' sulfonate. V a

D. Oil plusl).'75 per cent antioxidant plus 2 per c'ent'of the abovedescribed sodium diwaxdi- .benzothiophene sulfonate.

Cleanliness Rating 20 60 Hrs. Hrs. Hrs.

The above results show that the alkali and alkaline earth metal salts ofdiwaxdibenzothiophene sulfonic acid are effective additives in improvingthe characteristics of lubricating oils.

The above described lubricating compositions are, of course, merelyillustrative of those contemplated by the present invention.Antioxidants other than the pinene-phosphorus pentasulfide reactionproduct may be used. Likewise, various other improving agents may bepresent in the oil blend, such as V. I. agents, pour point depressants,oiliness agents, and the like.

This application is a division of our copending application, Serial No.756,812, filed June 24, 1947.

We claim:

1. As a new composition of matter, an alkyl dibenzothiophene sulfonicacid.

2. As a new composition of matter, a compound having the generalformula:

where R is an alkyl radical, R is selected from the group consisting ofhydrogen and analkyl radical and M is a metal.

3. As a new composition of matter, a compound having the generalformula:

RLUU R where R. is an alkyl radical, R is selected from the groupconsisting of hydrogen and an alkyl radical and M is a metal selectedfrom the group consisting of the alkali and alkaline earth metals.

where R. and R are alkylrradicals having between about 2 0 and about 30carbon atoms. I

6; As anew composition of matter, a .compound having th'general formula:

where R and R are alkyl radicals having between about 20 and aboutcarbon atoms. 7. As a new composition of matter, a compoun having thegeneral formula:

era

where R and R are alkyl radicals having between about 20 and about 30carbon atoms.

'FREDERICK P. RICHTER. I

EVERETT W. FULLER. 7

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES-PATENTS I Number Name "Date 2,438,955 Tryon Apr. 6, 1948

1. AS A NEW COMPOSITION OF MATTER, AN ALKYL DIBENZOTHIOPHENE SULFONICACID.